Winding device

ABSTRACT

The invention relates to a winding device for winding a travelling web of material, said winding device comprising at least one blade for slitting the web of material in the web direction into several partial webs of material and comprising a folding device for folding over the edges of the partial webs of material In order to provide a winding device that allows a web of material to be wound with folded over edges in the simplest possible manner and without folds, an oscillating device is provided, with which the at least one blade can be moved transversely to the direction of the web.

The invention relates to a winding device for winding a travelling webof material, said winding device comprising at least one blade forslitting the web of material in the web direction into several partialwebs of material and comprising a folding device for folding over theedges of the partial webs of material.

A winding device of this type is known from the U.S. Pat. No. 8,221,298B2 and is used, in particular, for winding stretch films.

Stretch films are used to secure and package individual items, forexample, on pallets. At the same time the items are wrapped with thestretch film, so that the items are connected to each other with the aidof the self-adhesive stretch film.

It has been found that the edges of stretch films are often the startingpoint for the film to tear during the wrapping operation on the pallet.Even minor damage to the edge of a stretch film roll can make this rollunusable, a feature that is particularly critical when the film is to beapplied by hand. Such damages may result, for example, from the finishedwound roll of stretch film being improperly handled during transport orbeing dropped on the ground.

Furthermore, it is also known that the stretch film is more resistant todamage if the edges are folded over or creased before the stretch filmis wound on a roll, with the effect that the stretch film is less likelyto tear. However, if the edges are folded over, the result is that theedges of the roll of film will be inadmissibly thick and hard duringstraight edge winding.

When folding over, it is necessary to cyclically offset the edges of thefilm to one side of the roll. This can be done, for example, bylaterally oscillating the reel or by means of angularly moveable guiderollers, after individual reel slitting.

However, reversing or oscillating the web of film prior to winding can,in turn, produce folds, which in turn may impair the function of thefilm.

Based on the aforesaid, the object of the present invention is toprovide a winding device that allows a web of material to be wound withfolded edges in the simplest possible manner and without folds.

This object is achieved by means of an oscillating device, with whichthe at least one blade can be moved transversely to the direction of theweb.

Hence, an essential element of the invention is the feature ofoscillating the cutter bar, used for slitting the reel, transversely tothe direction of the film. The devices for folding over the edges afterslitting the reel are fixed either on the same cutter bar and executeaccordingly the same oscillatory motion as the blades, or said foldingdevices are attached to a bar, which is located downstream of the cutterbar and which executes an oscillatory motion that is synchronized withthe cutter bar.

As a result, the folded over edges are laterally offset on the resultingstationary reel, and a winding with reduced edge structure is possible.In this case the stroke and frequency of the motion are adjustable andcan be adapted, if desired, as a function of the web speed, the filmthickness and the increasing diameter of the roll, so that the result isan optimal edge geometry.

For the subsequent folding device for producing the folded side edge,there are a number of variants. One variant consists of the feature thatone folding device is provided for each folded over edge. Each of thesefolding devices can be used either directly side by side or one afterthe other. It is also conceivable that the devices for folding over theedges dip centrally into the slit in order to start up, so that theyhave an effect on both edges; and, in the course of dipping, saidfolding devices are altered in position or shape due to the appropriatekinematics in such a way that they only affect one edge. This can bedone either simultaneously or sequentially for adjacent edges.

Another variant of a folding device consists of the feature of producinga strip cut-out of several reels and of removing said strip cutout bysuction. Then it would be possible to produce a space between the twoedges by means of the strip cutout, a design that allows the respectiveedges to be folded over separately.

The invention has a number of advantages over the prior art.

The prior art methods for lateral oscillation of the folded edges areoften very complex, since each one of the reels has to be oscillatedindividually after the reel slitting. For this purpose, additionaldevices are required that are usually expensive, complicated andmaintenance intensive.

According to the solution of the invention, there is also no limit withrespect to the width of the reel and the number of reels.

According to a preferred embodiment, it is provided that the oscillatingdevice comprises a driven belt, to which the at least one blade isattached. The belt may be, for example, a continuous toothed belt, whichis moved by a gearwheel, which is driven by an electric motor.

According to an additional preferred embodiment, it is provided that theoscillating device comprises a cutter bar, which is driven by a linearmotor and to which the at least one blade is attached.

In addition, preferably a control unit for actuating the oscillatingdevice is provided. As a result, the control device can be used tospecify all possible movements or, more specifically, slitting patterns.In particular, it is also conceivable that the thickness profile of thewound roll is continuously measured; and the oscillating device isactuated, as a function of the measured thickness profile, in such a waythat the result is a thickness profile that is as uniform as possible.

The invention may be applied in a particularly advantageous way to thewinding operation of stretch films that were produced on a cast filmextrusion line or a blown film line.

Additional details and advantages of the invention will be explainedbelow with reference to the accompanying drawings. The drawings show in:

FIG. 1 a first embodiment of the invention; and

FIG. 2 a second embodiment of the invention.

FIG. 1 shows a first embodiment of the invention. The web of material101 is a stretch film produced on a cast film extrusion line.

After the stretch film 101 has been produced, it is transported in thedirection 102 and, as a result, reaches the cutter bar 103. The cutterbar 103 is moved back and forth in the direction 104 by means of anoscillating device and has a total of five cutting blades 105. To theleft and the right of the edges there is in each instance a cut back 111and 112, which can be further processed for other purposes.

Behind the cutter bar 103 there are S-shaped strips 106, 107, 108 and109, and, in particular, approximately in the shape, as shown in FIG. 1.In this embodiment the S-shaped edge does not have to be uniform. Theamplitude and frequency of the movement of the oscillating device canalso be irregular. Moreover, it is also conceivable that the individualblades 105 are individually actuated and, therefore, execute a number ofdifferent movements.

FIG. 2 shows a second embodiment of the invention. The web of material201 is, once again, a stretch film produced on a cast film extrusionline.

After the stretch film 201 has been produced, it is transported in thedirection 202 and, as a result, reaches the cutter bar 203. The cutterbar 203 is moved back and forth in the direction 204 by means of anoscillating device and has a total of three cutting blades 205. Sincethe outermost edges are left untrimmed on the left and the right, thereis, in contrast to the embodiment according to FIG. 1, no cut back.

Behind the cutter bar 203 there are S-shaped strips 206, 207, 208 and209, and, in particular, approximately in the shape, as shown in FIG. 2,in this embodiment the S-shaped edge does not have to be uniform. Theamplitude and frequency of the movement of the oscillating device canalso be irregular. Moreover, it is also conceivable that the individualblades 205 are individually actuated and, therefore, execute a number ofdifferent movements.

The outer strips 206 and 209 have in each instance a straight edge andan S-shaped edge and are further processed in this shape for specificpurposes.

1. Winding device for winding a travelling web of material, comprisingat least one blade for slitting the web of material in the web directioninto several partial webs of material and comprising a folding devicefor folding over the edges of the partial webs of material,characterized by an oscillating device, with which the at least oneblade can be moved transversely to the direction of the web.
 2. Windingdevice, as claimed in claim 1, characterize in that the oscillatingdevice comprises a driven belt, to which the at least one blade isattached.
 3. Winding device, as claimed in claim 1, characterize in thatthe oscillating device comprises a cutter bar, which is driven by alinear motor and to which the at least one blade is attached.
 4. Windingdevice, as claimed in claim 1, characterize by a control unit foractuating the oscillating device.
 5. Winding device, as claimed in claim1, characterize in that the web of material is a stretch film producedon a cast film extrusion line or a blown film line.